未知题型 When the key is pressed, the 7-segment digital tube displays ’P’, and the LED is turned on. When the key is released, the 7-segment digital tube displays ’-’, and the LED is turned off. The key is connected to P3.2, as an interrupt 0 input.

单项选择题 氯气被液化是一个（）过程

未知题型 拔插头时，请勿直接拉电线，应拔插头，注意手部保持干爽（）